1. Field of the Invention
The present invention relates to a container opener for opening/closing a sealable container for containing and transferring a plurality of semiconductor wafers oriented horizontally and vertically arranged at predetermined intervals. More particularly, the invention relates to a front opening unified pod (FOUP) opener having a structure such that a drive section for a port door including a detachment/attachment mechanism for detaching/attaching a FOUP door and a holder mechanism for holding the FOUP door, and a drive section for a sensor mechanism for detecting presence/absence, storage condition, and position of wafers contained in the FOUP are arranged in an improved manner.
2. Description of the Related Art
A FOUP opener is adapted to establish communication between a space (a first control space) within a FOUP and a wafer transfer space (a second control space) and to enable transfer of wafers from the first control space to the second control space without exposure to the ambient atmosphere, by means of, for example, a robot. When the wafers are highly-precise wafers having a diameter of 300 mm or more, since such wafers are very expensive, the FOUP opener must satisfy a strict requirement for protection against wafer contamination with dust, specifically, dust particles generated by the FOUP opener itself must be reduced to one particle/b cft or less (0.1 xcexcm particles), and the mapping report error rate must be decreased to once/0.1-1 million wafers or less. In order to detect presence/absence, storage condition, or position of wafers contained in the FOUP before transfer of the wafers, mapping means is provided on either the FOUP opener or a robot. Generally, provision of the mapping means is optional for the FOUP opener and the robot.
FIG. 5 shows a conventional FOUP opener. As shown in FIG. 5, operation of a FOUP opener 01 for detaching a FOUP door 013 from and attaching the FOUP door 013 to/from an opening of a FOUP 010 and for moving the FOUP door 013 vertically is performed within a second control space 200 that maintains a clean room atmosphere. Accordingly, a drive section of a horizontal-movement mechanism 040 for moving a port door 023 and a sensor 070 horizontally and a drive section of a vertical-movement mechanism 050 for moving the port door 023 and the sensor 070 vertically are disposed within the second control space 200. The port door 023 includes a detachment/attachment mechanism for detaching/attaching the FOUP door 013 and a holder mechanism for holding the FOUP door 013 (see Japanese Patent Application Laid-Open (Kokai) No. 11-145244). Reference numeral 014 denotes a semiconductor wafer, reference numeral 021 denotes a port plate, and reference numeral 300 denotes the ambient atmosphere.
Thus, there has been the problem that the drives, which are dust generators, contaminate the second control space 200, which must maintain a clean atmosphere. For example, when a movable member is actuated by a motor or cylinder of a drive section, friction causes generation of dust, which is scattered within a clean room (the second control space 200). Also, an organic substance generated through vaporization of a lubricant applied to a movable member may be scattered within the clean room 200. As a result, the clean room 200 fails to maintain a high level of cleanliness. Furthermore, when the drive sections are to be serviced for maintenance, inspection, or repairs, within the clean room 200, a worker must move or remove equipment in order to establish work space within the clean room 200, resulting in scattering of dust within the clean room 200. Thus, restoration of cleanliness within the clean room 200 to a regular, high level consumes a considerably great amount of time and cost. In order to enable a worker to work within the clean room 200, equipment for removing dust from the worker must be installed, thus incurring further cost.
In order to cope with the above problem, a FOUP opener as shown in FIG. 6 has been proposed (see Japanese kohyo (PCT) Patent Published (re-published) No. W099/28965). As shown in FIG. 6, a port door is disposed outside a clean room (a second control space 200) for opening/closing and vertical movement of a FOUP door outside the clean room 200. However, since a port door 023 is located between a FOUP 010 and a port plate 021, a gap g is formed therebetween. The gap g creates the possibility of entry of dust into the FOUP 010 (first control space 100) and into the clean room 200 from outside the clean room 200 (from the ambient atmosphere 300), possible adhesion of the dust to the inside surface of FOUP door 013 and to the outside surface of the port door 023, and possible outflow of a large amount of highly clean air to the exterior of the clean room 200.
In the case of the FOUP opener 01 of the patent publication, as the gap g between the FOUP 010 and the port plate 021 becomes larger, the positioning accuracy of the FOUP 010 is reduced due to machining errors, assembly errors, and wear of dock plate 031 for carrying and positioning the FOUP 010 and components of a dock moving mechanism 030. Thus, the presence/absence, storage condition, and position of wafers 014 contained in the FOUP 010 cannot be detected with high accuracy, thus creating possible problems in transfer of the wafers 014.
An object of the present invention is to solve the above-mentioned problems in the conventional FOUP openers and to provide a FOUP opener which does not cause contamination of a clean room (a second control space) by contaminants generated by drives of horizontal- and vertical-movement mechanisms for a port door and a sensor; which does not allow entry of dust into a FOUP (first control space) or into the clean room from the ambient atmosphere.
Another object is to prevent adhesion of dust to the inside surface of a FOUP door and to the outside surface of the port door.
Yet another object is to prevent outflow of a large amount of highly clean air to the exterior of the clean room.
Still another object is to reduce the gap between the FOUP and a port plate, to thereby avoid impairment of accuracy in positioning of the FOUP due to machining errors, assembly errors, and wear of a dock plate and components of a dock moving mechanism, so that a mapping sensor can maintain high detection accuracy to avoid possible problems in transfer of the wafers.
To achieve the above objects, the present invention provides a drive-section-isolated FOUP opener for opening and closing a FOUP door which closes a front opening portion of a FOUP containing a plurality of semiconductor wafers oriented horizontally and vertically arranged at predetermined intervals. The FOUP opener comprises a dock plate for carrying and positioning the FOUP; a dock moving mechanism for moving the dock plate to a position for detachment and attachment of the FOUP door; a port door including a detachment/attachment mechanism for detaching and attaching the FOUP door and a holder mechanism for holding the FOUP door; a port plate including an opening, the opening being closed by the port door; a port door horizontal-movement mechanism for horizontally moving the port door; a sensor horizontal-movement mechanism for horizontally moving a sensor bracket, the sensor bracket having a mapping sensor mounted on an upper portion thereof and adapted to detect presence/absence, storage condition, and position of wafers contained in the FOUP; and a port-door-and-sensor vertical-movement mechanism for vertically moving the port door and the sensor bracket with the port door holding the FOUP door. A drive section of the port door horizontal-movement mechanism, a drive section of the sensor horizontal-movement mechanism, and a drive section of the port-door-and-sensor vertical-movement mechanism are disposed on the opposite side of the port plate relative to a clean room, with the clean room housing the port door and the sensor bracket.
Thus, in the drive-section-isolated FOUP opener of the present invention, the drive section of the port door horizontal-movement mechanism, the drive section of the sensor horizontal-movement mechanism, and the drive section of the port-door-and-sensor vertical-movement mechanism are disposed outside the clean room (the second control space), which houses the port door and the sensor bracket, i.e., on the side of the port plate opposite the clean room and thereby isolated from the clean room.
As a result, the port plate prevents dust generated by the drive sections from entry into the clean room. For example, when a movable member actuated by a motor or cylinder of a drive section generates dust through friction, the dust is not scattered into the clean room. Also, an organic substance generated through vaporization of a lubricant applied to a movable member does not enter the clean room. Furthermore, when the drive sections are to be serviced for maintenance, inspection, or repairs, a worker does not need to enter the clean room; i.e., the worker does not need to move or remove equipment in order to establish work space within the clean room, thereby avoiding contamination of the clean room with dust associated with such work. Therefore, the clean room can maintain a high level of cleanliness.
Since a worker does not need to enter the clean room when the drive sections are to be serviced for maintenance, inspection, or repairs, there is no need to install equipment for removing dust from the worker who is to enter the clean room for performing service work, thereby lowering equipment expenses.
Since the port door is disposed within the clean room, the gap between the FOUP and the port plate can be zero or very small. Because the gap therebetween is very small, entry of dust into the FOUP (first control space) and into the clean room from ambient atmosphere is avoided, along with avoidance of adhesion of the dust to the inside surface of the FOUP door and the outside surface of the port door as well as outflow of a large amount of highly clean air from the clean room. Thus, the clean room can more reliably maintain a high level of cleanliness.
Furthermore, since the gap between the FOUP and the port plate is small, inaccuracy in positioning of the FOUP due to machining errors, assembly errors, and wear of the dock plate and components of the dock moving mechanism can be avoided. Thus, the mapping sensor can maintain high detection accuracy, so that wafers can be transferred with high reliability.
Preferably, the port plate has a vertically extending guide slit located underneath its opening, and the drive section of the port door horizontal-movement mechanism, the drive section of the sensor horizontal-movement mechanism, and the drive section of the port-door-and-sensor vertical-movement mechanism move the port door and the sensor bracket horizontally or vertically, via the guide slit.
Thus, entry of dust into the clean room through the guide slit from outside the clean room and outflow of a large amount of highly clean air to the exterior of the clean room through the guide slit can be suppressed to the greatest possible extent, thereby contributing to the maintenance of a high level of cleanliness in the clean room. While arms of the port door and sensor bracket move along the guide slit, thereby possibly generating dust, the dust can be ejected to the exterior of the clean room from the guide slit through employment of a clean room pressure (a positive clean room pressure) higher than pressure outside the clean room. Thus, this feature also contributes to the maintenance of a high level of cleanliness in the clean room.
Preferably, the guide slit is used in common for moving the port door and the sensor bracket. Thus, the number of guide slits can be minimized to thereby enhance the aforementioned effects.
Preferably, the drive-section-isolated FOUP opener of the present invention further comprises a drive section chamber for housing the drive section of the port door horizontal-movement mechanism, the drive section of the sensor horizontal-movement mechanism, and the drive section of the port-door-and-sensor vertical-movement mechanism. The drive section chamber includes a device for exhausting atmosphere from the drive section chamber to the exterior. Thus, entry of dust generated in the drive sections into the clean room through the guide slit can be completely prevented, thereby more reliably maintaining the clean room at a high level of cleanliness.